In situations where pipes need to be connected together in a semi-permanent fashion, each pipe end is fitted with a flange, and the flanges are bolted together. There are several types of flanges, defined in part by the type of sealing surface provided on each flange face. For example, a raised face flange has a sealing surface that is raised in relation to the portion of the flange through which bolts extend, and the raised face is either smooth or has shallow circular grooves. When mating raised face flanges, a gasket material is positioned between the raised faces and held in place by compressive forces supplied by the bolts. A ring-type joint (RTJ) flange is yet another example of a type of flange. RTJ flanges have a circular ring groove on the flange face. A metallic ring, or ring gasket, is placed between two RTJ flanges in the ring groove, and the ring gasket is deformed or “coined” between the flanges to provide a seal. The compressive forces to deform the ring supplied by the bolts.
In addition to different types of flanges, there are also different ratings for flanges, even of the same type. For example, a raised face flange for 30 inch pipe may come in a variety of ANSI ratings directly related to the internal pressure expected in the pipe. Size of the sealing surface for raised face flanges may vary slightly from flange-to-flange for a given flange size, in spite of each flange having a central passage of the same internal diameter. Likewise, the depth, width and/or location of a ring groove for RTJ flanges may change for different pressure ratings or may vary slightly from flange-to-flange in spite of each flange having a central passage of the same internal diameter.
Ultrasonic flow meters are used to measure fluid flow (e.g., natural gas, oil, water) in a pipe. In some situations, ultrasonic meters are used to measure fluid flow for custody exchange purposes, and thus particular accuracy is needed. In order to verify the accuracy of an ultrasonic meter, new meters (and possibly rebuilt meters) require a flow calibration at a testing laboratory. However, selection of a flange type and pressure rating for a meter is customer dependent. Situations thus occur where a testing laboratory has a set of piping having an internal diameter matching that of an ultrasonic meter (e.g., 30 inches), as required by testing standards, but the testing laboratory may have flanges with different seal types and/or different pressure ratings. For example, the testing laboratory may use RTJ flanges having first pressure rating, and the meter to be tested may use raised face flanges having different pressure ratings than the RTJ flanges. Testing laboratories have addressed the issue in the past by having a plurality of pipe “spools” with each spool having different flange type on the meter end. However, construction and storing such spools is expensive, in some cases costing more than the meter to be tested.